#4 United States of America

The United States has a mobile internet penetration of 36 percent. Some 88 percent of U.S. adults own a cell phone of some kind as of April 2012, and more than half of these cell owners like 55 percent of them use their phone to go online according to a report by national telephone survey conducted in March -April 2012.

Also in the next three years, the number of U.S. mobile Internet users will increase by a compound annual growth rate of 16.6 percent while PCs and other wireline services first stagnate, then gradually decline, Yahoo Finance predicts.

#3 United Kingdom

Nearly half of the UK internet users are going online using mobile phones as per the report by Office for National Statistics.

The country stands third in this list with mobile internet penetration rate of 44 percent, which is slowly catching up with Australia. The increased impact of Smartphones and tablets in the UK are responsible for the decline in internet access by traditional computers. Also, around 71 percent of 16 to 24-year-olds use the internet via their mobile phone.